There are various springs, such as wire springs, flat springs, special springs, etc. The wire springs comprise the compression straight springs, the tension straight spring, the torsion spiral spring, the conical spring, and so forth.
The wire springs are generally the straight spring and the conical spring, as shown in FIGS. 1 and 2. Under the circumstance that the greatest stress of the straight spring does not exceed the elastic limit of the straight spring, the elasticity of the straight spring is eventually undermined after the prolonged use of the straight spring, as illustrated in FIG. 1.
As illustrated in FIG. 2, the conical spring is defective in design in that the base portion of the spring is caused to deform first when the conical spring is exerted on by a load, and that the midsegment and the top portion of the conical spring are subsequently caused to deform. As a result, the use of the conical spring can not be easily controlled.